POS0157 POST-STRESS ELASTOGRAPHIC DIFFERENCES AT ACHILLES ENTHESIS AS AN OUTCOME MEASURE IN THE ASSESMENT OF PATIENTS WITH PSORIATIC ARTHRITIS IN REMISSION
Authors: C. Guillén-Astete, A. Palomeque, M. Serrano Warleta, R. Manzo
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Tendon elastography has demonstrated the ability to discriminate between healthy subjects and patients with spondyloarthritis. Its greatest strength is its ability to reliably quantify the stiffness of a soft structure. However, its use in anatomical load-bearing entheses has not been sufficiently explored. The use of quantifiable enthesis assessment methods would open up multiple possibilities in both the diagnosis and follow-up of inflammatory enthesis diseases. <h3>Objectives</h3> To evaluate the response to mechanical stress through elastography in the enthesis of the Achilles tendon among patients with psoriatic arthritis (PsA) in remission treated with anti-IL17 therapies, with other non-anti-IL17 therapies, and healthy controls. <h3>Methods</h3> Observational, multicenter, non-blind study. The elastography results before and after physical exercise of patients with PsA in remission treated with therapies aIL17, therapies other than aIL17 (non-aIL17) were compared with those of healthy subjects matched by age (+/- 4 years), sex, and body fat percentage (BFP) (+/- 4%). Elastography was performed with a GE Logic S8 sonograph with a linear 6MHz probe. The region of interest (ROI) was the Achilles' enthesis identified distal to the vertex of the pre-Achilles bursa choosing the greatest thickness in the longitudinal plane. Each assessment was the result of the average of five consecutive determinations. Body composition was determined using an OMROM Healthcare model BF511 impedance meter. Physical exercise performed on a SALTER activeHealth PT-0083 magnetic bike, at an intensity of +80% and up to 300Kcal. A before and after analysis was performed using the T-Student's test for interdependent samples. The main outcome variable was the variability of the Achilles enthesis stiffness after physical exertion. <h3>Results</h3> The elastographic results of 14 patients on aIL17 therapies, 15 on non-aIL17 therapies, and 28 healthy controls were compared. The demographic and constitutional distribution was homogeneous in the three groups (p=0.221 for age, p=0.983 for BFP). The Achilles enthesis height ± standard deviation (mm) in controls was 4.27 ± 0.45 in controls, 4.78 ± 0.56 in non-aIL17 patients, and 4.66 ± 0.47 in aIL17 patients (p=.005 in controls vs. non-aIL17). Baseline, enthesis rigidity in the controls, aIL17 and non-aIL17 group was 210.2±21.9, 183.7±7 and 201.17±6.1 Kpa, respectively (p&lt;.001 in controls vs. non-aIL17, p=.016 in non-aIL17). aIL17 vs. aIL17). After exercising, the same measurements were 227.5±21.2, 195.3±8.3, and 219.1±9.1 Kpa (p&lt;.001 in control vs. non-aIL17, p&lt;.001 in non-aIL17 and aIL17). The change experienced in the stiffness after the effort given between the three groups determined a mean change of 17.3±29.5 Kpa (t=3.113, p=.004) in the controls, of 5.1±3 Kpa (t=6.52, p&lt;.001) in the non-aIL17 group and 17.9±6.5 Kpa (t=10.303, p&lt;.001) in the aIL-17 group. The increases in stiffness with exercise were comparable between controls and the aIL-17 group (p=.919), and both were significantly higher than the non-aIL-17 group (p&lt;.001). <h3>Conclusion</h3> In patients in remission, the known immediate adaptability of the entheses to physical exercise through increased rigidity can be verified by elastography in patients with PsA and controls. Patients treated with aIL17 therapies exhibited adaptive elastographic responses to enthesis exercises that were indistinguishable from healthy controls and significantly higher than those not treated with aIL17. These findings lay the groundwork for using elastography as an outcome variable in the evolutionary study of entheses in patients with other forms of spondyloarthritis. <h3>References</h3> NIL. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Carlos Guillén-Astete Speakers bureau: Janssen, Novartis, Galapagos, Paid instructor for: Novartis, Janssen, Galapagos, Consultant of: Novartis, Galapagos, Janssen, Grant/research support from: Grunenthal, Novartis, Aliuska Palomeque: None declared, Marta Serrano Warleta: None declared, Rosa Manzo: None declared.